SCJP题库.docx
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SCJP题库
yModule1-JAVA基础
一、选择题：
Question1
Given:
35.String#name="JaneDoe";
36.int$age=24;
37.Double_height=123.5;
38.double~temp=37.5;
Whichtwoaretrue?
（Choosetwo.）
A.Line35willnotcompile.
B.Line36willnotcompile.
C.Line37willnotcompile.
D.Line38willnotcompile.
Answer:
AD标识符以字母，下划线，或者$开始
Question2
Given:
11.publicclassTest{
12.publicstaticvoidmain（String[]args）{
13.intx=5;
14.booleanb1=true;
15.booleanb2=false;
16.
17.if（（x==4）&&!
b2）
18.System.out.print（"l"）;
19.System.out.print（"2"）;
20.if（（b2=true）&&b1）
21.System.out.print（"3"）;
22.}
23.}
Whatistheresult?
A.2
B.3
C.12
D.23
E.123
F.Compilationfails.
G.Anexceptionalisthrownatruntime.
Answer:
D注意20行，=为赋值，不要被骗
Question3
Given:
42.publicclassClassA{
43.publicintgetValue（）{
44.intvalue=0;
45.booleansetting=true;
46.Stringtitle="Hello";
47.if（value||（setting&&title=="Hello"））{return1;}
48.if（value==1&title.equals（"Hello"））{return2;}
49.}
50.}
And:
70.ClassAa=newClassA（）;
71.a.getValue（）;
Whatistheresult?
A.1
B.2
C.Compilationfails.
D.Thecoderunswithnooutput.
E.Anexceptionisthrownatruntime.
Answer:
C编译不通过，47行value为int类型不是boolean
Question4
Given:
11.publicvoidtestIfA（）{
12.if（testIfB（"True"））{
13.System.out.println（"True"）;
14.}else{
15.System.out.println（"Nottrue"）;
16.}
17.}
18.publicBooleantestIfB（Stringstr）{
19.returnBoolean.valueOf（str）;
20.}
WhatistheresultwhenmethodtestIfAisinvoked?
A.True
B.Nottrue
C.Anexceptionisthrownatruntime.
D.Compilationfailsbecauseofanerroratline12.
E.Compilationfailsbecauseofanerroratline19.
Answer:
A19行，如果str为true则返回ture，否则返回false
Question5
Given:
11.publicstaticvoidmain（String[]args）{
12.Integeri=newInteger
（1）+newInteger
（2）;
13.switch（i）{
14.case3:
System.out.println（"three"）;break;
15.default:
System.out.println（"other"）;break;
16.}
17.}
Whatistheresult?
A.three
B.other
C.Anexceptionisthrownatruntime.
D.Compilationfailsbecauseofanerroronline12.
E.Compilationfailsbecauseofanerroronline13.
F.Compilationfailsbecauseofanerroronline15.
Answer:
A就是两个Integer类型相加
Question6
Given:
11.publicstaticvoidmain（String[]args）{
12.Stringstr="null";
13.if（str==null）{
14.System.out.println（"null"）;
15.}else（str.length（）==0）{
16.System.out.println（"zero"）;
17.}else{
18.System.out.println（"some"）;
19.}
20.}
‘Whatistheresult?
A.null
B.zero
C.some
D.Compilationfails.
E.Anexceptionisthrownatruntime.
Answer:
D这题真恶心15行少个if
Question7
Given:
10.intx=0;
11.inty=10;
12.do{
l3.y--;
14.++x;
15.}while（x<5）;
16.System.out.print（x+","+y）;
Whatistheresult?
A.5,6
B.5,5
C.6,5
D.6,6
Answer:
B（91，82，73，64，55）没啥争议
Question8
Given:
25.intx=12;
26.while（x<10）{
27.x--;
28.}
29.System.out.print（x）;
Whatistheresult?
A.0
B.10
C.12
D.Line29willneverbereached.
Answer:
C12>10，所以直接跳出循环，输出x=12
Question9
Given:
35.intx=10;
36.do{
37.x--;
38.}while（x<10）;
Howmanytimeswillline37beexecuted?
A.tentimes
B.zerotimes
C.onetometimes
D.morethantentimes
Answer:
D死循环
Question10
Given:
11.publicstaticvoidmain（String[]args）{
12.for（inti=0;i<=10;i++）{
13.if（i>6）break;
14.}
15.System.out.println（i）;
16.}
Whatistheresult?
A.6
B.7
C.10
D.11
E.Compilationfails.
F.Anexceptionisthrownatruntime.
Answer:
E15行i超出了作用域
Question11
Given:
55.int[]x={1,2,3,4,5};
56.inty[]=x;
57.System.out.println（y[2]）;
Whichistrue?
A.Line57willprintthevalue2.
B.Line57willprintthevalue3.
C.Compilationwillfailbecauseofanerrorinline55.
D.Compilationwillfailbecauseofanerrorinline56.
Answer:
B没争议，考察数组下标是从0开始
Question12
Whichtwocodefragments（片段）correctly（正确）createandinitializeastaticarrayofintelements?
（Choosetwo.）
A.staticfinalint[]a={100,200};
B.staticfinalint[]a;
static{a=newint[2];a[0]=100;a[1]=200;}
C.staticfinalint[]a=newint[2]{100,200};
D.staticfinalint[]a;
staticvoidinit（）{a=newint[3];a[0]=100;a[1]=200;}
Answer:
ABc不能指定长度，d不能在init方法中赋值，要么在static代码块中
Question13
Given:
11.publicstaticvoidmain（String[]args）{
12.Objectobj=newint[]{1,2,3};
13.int[]someArray=（int[]）obj;
14.for（inti:
someArray）System.out.print（i+""）
15.}
‘Whatistheresult?
A.123
B.Compilationfailsbecauseofanerrorinline12.
C.Compilationfailsbecauseofanerrorinline13.
D.Compilationfailsbecauseofanerrorinline14.
E.AClassCastExceptionisthrownatruntime.
Answer:
A没争议，foeach循环遍历数组
Question14
Given:
11.String[]elements={"for","tea","too"};
12.Stringfirst=（elements.length>0）?
elements[0]:
null;
Whatistheresult?
A.Compilationfails.
B.Anexceptionisthrownatruntime.
C.Thevariablefirstissettonull.
D.Thevariablefirstissettoelements[0].
Answer:
D
Question15
Given:
10.publicclassBar{
11.staticvoidfoo（int...x）{
12.//insertcodehere
13.}
14.}
Whichtwocodefragments,insertedindependently（独立的）atline12,willallowtheclasstocompile?
（Choosetwo.）
A.foreach（x）System.out.println（z）;
B.for（intz:
x）System.out.println（z）;
C.while（x.hasNext（））System.out.println（x.next（））;
D.for（inti=0;iAnswer:
BDx相当于一个数组，a明显错没有foreach，c中x没有hadNext方法
Question16
Aprogrammer（程序员）needstocreatealoggingmethodthatcanaccept（接受）anarbitrary（随意任意）numberofarguments.Forexample,itmaybecalledinthese
ways:
logIt（"logmessage1"）;
logIt（"logmessage2”,”logmessage3"）;
logIt（"logmessage4","logmessage5","logmessage6"）;
Whichdeclaration（说明）satisfies（符合）thisrequirement（需求）?
A.publicvoidlogIt（String*msgs）
B.publicvoidlogIt（String[]msgs）
C.publicvoidlogIt（String...msgs）
D.publicvoidlogIt（Stringmsg1,Stringmsg2,Stringmsg3）
Answer:
C可变长参数
Question17
1.publicclassA{
2.publicStringdoit（intx,inty）{
3.return"a";
4.}
5.
6.publicStringdoit（int...vals）{
7.return"b";
8.}
9.}
Given:
25.Aa=newA（）;
26.System.out.println（a.doit（4,5））;
Whatistheresult?
A.Line26prints"a"toSystem.out.
B.Line26prints"b"toSystem.out.
C.Anexceptionisthrownatline26atruntime.
D.CompilationofclassAwillfailduetoanerrorinline6.
Answer:
A确定参数和可变长参数同时存在的时候，优先考虑确定参数的
Question18
GivenafileGrizzlyBear.java:
1.packageanimals.mammals;
2.
3.publicclassGrizzlyBearextendsBear{
4.voidhunt（）{
5.Salmons=findSalmon（）;
6.s.consume（）;
7.}
8.}
andanotherfile,Salmon.java:
1.packageanimals.fish;
2.
3.publicclassSalmonextendsFish{
4.voidconsume（）{/*dostuff*/}
5.}
Assume（假定）bothclassesaredefinedinthecorrectdirectoriesfortheftpackages,andthattheMammalclasscorrectlydefinesthefindSalmon（）method.Whichtwochangesallowthiscodetocompilecorrectly?
（Choosetwo.）
A.addpublictothestartofline4inSalmon.java
B.addpublictothestartofline4inGrizzlyBear.java
C.addimportanimals.mammals.*;atline2inSalmon.java
D.addimportanimals.fish.*;atline2inGrizzlyBear.java
E.addimportanimals.fish.Salmon.*;atline2inGrizzlyBear.java
F.addimportanimals.mammals.GrizzlyBear.*;atline2inSalmon.java
Answer:
AD调用不同包下的类，要先导入，方法权限要设置成public
Question19
Given:
10.packagecom.sun.scjp;
11.publicclassGeodetics{
12.publicstaticfinaldoubleDIAMETER=12756.32;//kilometers
13.}
Whichtwocorrectlyaccess（访问）theDIAMETERmemberoftheGeodeticsclass?
（Choosetwo.）
A.importcom.sun.scjp.Geodetics;
publicclassTerraCarta{
publicdoublehalfway（）
{returnGeodetics.DIAMETER/2.0;}}
B.importstaticcom.sun.scjp.Geodetics;
publicclassTerraCarta{
publicdoublehalfway（）{returnDIAMETER/2.0;}}
C.importstaticcom.sun.scjp.Geodetics.*;
publicclassTerraCarta{
publicdoublehalfway（）{returnDIAMETER/2.0;}}
D.packagecom.sun.scjp;
publicclassTerraCarta{
publicdoublehalfway（）{returnDIAMETER/2.0;}}
Answer:
ACb中不能静态导入类，c中静态导入类属性，正确，d访问错误很明显
Question20
Givenclassesdefinedintwodifferentfiles:
1.packageutil;
2.publicclassBitUtils{
3.privatestaticvoidprocess（byte[]b）{}
4.}
1.packageapp;
2.publicclassSomeApp{
3.publicstaticvoidmain（String[]args）{
4.byte[]bytes=newbyte[256];
5.//insertcodehere
6.}
7.}
Whatisrequired（必需的）atline5inclassSomeApptousetheprocessmethod
ofBitUtils?
A.process（bytes）;
B.BitUtils.process（bytes）;
C.app.BitUtils.process（bytes）;
D.util.BitUtils.process（bytes）;
E.importutil.BitUtils.*;process（bytes）;
F.SomeAppcannotusetheprocessmethodinBitUtils.
Answer:
F私有的，不能被访问
Question21
GivenaclassRepetition（重复）:
1.packageutils;
2.
3.publicclassRepetition{
4.publicstaticStringtwice（Strings）{returns+s;}
5.}
andgivenanotherclassDemo:
1.//insertcodehere
2.
3.publicclassDemo{
4.publicstaticvoidmain（String[]args）{
5.System.out.println（twice（"pizza"））;
6.}
7.}
Whichcodeshouldbeinsertedatline1ofDemo.javatocompileandrunDemotoprint“pizzapizza”?
A.importutils.*;
B.staticimportutils.*;
C.importutils.Repetition.*;
D.staticimportutils.Repetition.*;
E.importutils.Repetition.twice（）;
F.importstaticutils.Repetition.twice;
G.staticimportutils.Repetition.twice;
Answer:
F静态导入
Question22
Given:
1.packagetest;
2.
3.classTarget（目标）{
4.publicStringname="hello";
5.}
Whatcandirectly（直接的）accessandchangethevalueofthevariable（变量）name?
A.anyclas
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